Implants are delivered to a vascular site, such as an aneurysm, of a patient via a microcatheter to occlude or embolize the vascular site. Typically, the implant is engaged at the distal end of either the delivery microcatheter or the guidewire contained within the microcatheter and controllably released therefrom into the vascular site to be treated. The clinician delivering the implant must navigate the microcatheter or guide catheter through the vasculature and, in the case of intracranial aneurysms, navigation of the microcatheter is through tortuous microvasculature. This delivery may be visualized by fluoroscopy or another suitable means. Once the distal tip of the catheter or guidewire is placed in the desired vascular site, the clinician must then begin to articulate the implant in the vascular site to ensure that the implant will be positioned in a manner to sufficiently embolize the site. Once the implant is appropriately positioned, the clinician must then detach the implant from the catheter or guidewire without distorting the positioning of the implant. Detachment may occur through a variety of means, including, chemical detachment, mechanical detachment, hydraulic detachment, and thermal detachment.
The procedure of delivering the implant to the vascular site can be complicated for a number of reasons. One common complication found with implants of the art is that the doctor is not able to effectively articulate, rotate, and/or control the implant during positioning in the vascular site to provide sufficient embolization. One reason that the implant may not be able to effectively articulate is that the proximate portion of the implants of the art are often rigid. This portion is referred to as the “stiff zone” and may also contain the detachment mechanism. One drawback of an implant having a “stiff zone” is that this “stiff zone” may cause catheter kick-out after deployment of the implant to the vascular site.
Another complication with implants of the art is that the implant may not be able to substantially conform to the vascular site due the presence of a stretch-resistant member. For example, U.S. Pat. No. 5,582,619 teaches a stretch-resistant member that is fixedly attached at both ends or at one end and then at another point in the lumen of the catheter. Due to the stretch-resistant member being fixedly attached in two locations, the implant, after delivery, will maintain some stretch-resistant properties. If the implant is stretch resistant after delivery, this may inhibit the implant's ability to substantially conform to the vascular site.
Yet another complication with implants of the art is that after detachment, the implant may contain a traumatic (or sharp) portion or stem. This traumatic portion most frequently occurs with implants that are mechanically or electrolytically detached from the delivery device. See, for example, U.S. Publ. 2004/0034363 which describes use of a stretch-resistant member and a loop at the proximal end of the coil. The loop, after deployment, is a traumatic portion. The traumatic portion may cause damage to the patient in the surrounding vasculature. Further, it is also contemplated that due to the presence of the loop, the clinician is not able to torque the implant during delivery therefore making the appropriate placement more difficult.
In light of the above, there exists a need for an implant that maintains the ability to freely articulate and torque without having a “stiff zone,” and also for the implant to substantially conform to the vascular site. There also exists a need to have an implant without a traumatic portion or stem after detachment at the vascular site.